With changes of eras and advancement of science and technology, there are increasing vehicles around people, and speeds of the vehicles are becoming higher. Based on actually measured data of communications operators and theoretical analysis of mobile communications in a high-speed environment, mobile communications in a high-speed environment has many problems in comparison with conventional cellular network communications.
In the prior art, if user equipment (UE) in a high-speed moving state (for example, in a high speed train) performs radio resource management such as measurement, cell selection or reselection, handover, and radio link monitoring still by using a radio resource management (RRM) algorithm parameter in an ordinary cellular network, because the UE moves at a quite high speed, a situation shown in FIG. 1 easily occurs. Although the UE passes through a target cell, RRM cannot be well completed.
For example, UE is located in a high speed train (HST) at a speed of 350 km/h, and cells are at intervals of 500 meters. If the UE in an idle state performs cell reselection by using a discontinuous reception (DRX) cycle of 0.32 seconds in an ordinary cellular network, provided that the UE completes identification and evaluation on an intra-frequency cell within 36 DRX cycles (that is, 11.52 seconds), a reselection condition may be satisfied. However, according to a requirement of 11.52 seconds, a maximum distance traveled by the UE may be 1120 meters. Therefore, a case in which the UE has passed through a target cell but still cannot camp on the target cell easily occurs. Consequently, system performance is severely degraded.
How to satisfy an RRM requirement in a high-speed mobile communication environment and ensure and improve network performance is a current research hotspot.